1. Preparation of immobilization matrix with low oxygen permeabilityPreparation of immobilization matrix with low ozygen permeability was tried with alginate gel as a model matrix. Effects of alginate composition and gelling condition on diffusional and mechanical properties of alginate gel were investigated first. Effects of gelling cation on effective diffusivity of oxygen, nitrate and glucose in alginate gel were also measured. Based on the results obtained, barium-alginate gel was found to meet the conditions required for immobilization of denitrifier ; that is, low oxygen permeability as well as high permeability of nitrate and glucose.2. Immobilization of denitrifier with in barium-alginate gelImmobilization of denitrifier with in barium-alginate gel had no adverse effect on denitrification activity. That is, denitrification rate of the immobilized denitrifier was almost equal to that of the suspended denitrifier under anaerobic condition. The denitrification activity of the Ba-a
… Morelginate immobilized denitrifier was above 90%, based on that under anaerobic condition, even if the bulk DO concentrations up to about 3 mg/L.Denitrification was successfully carried out by the immobilized denitrifier under aerobic condition.3. Aerobic denitrification by the immobilization denitrifierInitial cell loading and beads diameter were optimized in preparation of the immobilized denitrifier. Effect of organic matter, temperature and pH on denitrification rate of the immobilized denitrifier were also investigated under aerobic condition. Kinetic parameters for design of the aerobic denitrification by the immobilized denitrifier were obtained.It was concluded that barium-alginate gel was most suitable for immobilization of denitrifier and that denitrification by the immobilization denitrifier was carried out successfully even if the bulk DO concentrations up to about 3 mg/L.The results obtained in this project are expected to contribute for prevention of nitrogen pollution of aquatic environment. Less